No I can't, you promised not to mention my chess inability.
What strange chess rules can you think up?

No I can't, you promised not to mention my chess inability.
I have already have mentioned all your other inabilities so I thought I would drag that out too.

No clocks. When it is your turn to move you have to hold your breath, and you can't release until you move.

Tuesday Knight Madness Chess. If its Tuesday night, all your Knights have to face the "wrong" way. Backwards. Complaining that this caused you to lose is allowed, but strongly discouraged.

Lasker chess. You have to dress up like your favorite historical chess player. Whoever chooses Emmanual Lasker wins.
No clocks. When it is your turn to move you have to hold your breath, and you can't release until you move.
Been done:
http://www.msoworld.com/2013/07/diving-chess/

@wiener: finally the Halloween gambit is completely sound!
I'm not much of a chess player so I don't know what that means, sorry, lol.
Blindfold chess boxing .. you have to play the game while you are in the ring by calling out the moves while you are boxing .. Win by knockout or Checkmate whichever comes first .. Tie if you can call out a mate before you hit the ground...
A variant of this is if both players really are blindfolded...

Tuesday Knight Madness Chess. If its Tuesday night, all your Knights have to face the "wrong" way. Backwards. Complaining that this caused you to lose is allowed, but strongly discouraged.
I Love it that even though "complaining" about the knights is not Actually against the rules, it should be considered "poor form."
"Sorry, old chap, but I'm rather afraid I feel obliged to tell you that I found that last remark to be not only ill-considered, but, if I may say so, quite unworthy of a true gentleman."
That'll get 'em. :-)
No eating yoghurt; it might have secret messages from your fans.